When in DC, you have to get Ethiopian food! The DC area is home to the largest Ethiopian population outside Addis Ababa, so the food is really authentic and good. And it is very veggie-friendly too. For the most authentic, try Habesha Market, but it's like a deli where all the Ethiopians eat. For a nice sit-down meal (not pricey though) go to Etete. For a fun cultural experience with live music and dance as well, go to Dukem. Bonus: they're all within easy walking distance from each other, so you can take a look for yourself and decide. Not walking distance from Capitol Hill, but very easy to get to by Metro.